Work machine and control system for work machine

ABSTRACT

A bulldozer includes: a travel manipulation lever that receives a manipulation of an operator and outputs a travel command to allow a travel device to travel or to stop the travel device; a fuel adjustment dial that sets a rotation speed of an engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; a monitor that performs notification to the operator; and a controller. When the travel command to allow the travel device to travel is issued from the travel manipulation lever, a set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller causes the monitor to perform the notification.

TECHNICAL FIELD

The present disclosure relates to a work machine, and a control system for the work machine.

BACKGROUND ART

Japanese Patent Laying-Open No. 2005-233420 (PTL 1) discloses a hydrostatic transmission vehicle that travels by converting an output of an engine using a hydrostatic transmission. The hydrostatic transmission includes a variable capacity pump driven by the engine, and a variable capacity hydraulic motor that rotates by receiving a hydraulic oil of the variable capacity pump. By changing the angle of a swash plate of the variable capacity pump or the variable capacity hydraulic motor, the capacity of the hydrostatic transmission is changed, and thereby the output of the engine that can be absorbed by the hydrostatic transmission can be changed, or a vehicle speed of a work vehicle can be changed.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laying-Open No. 2005-233420

SUMMARY OF INVENTION Technical Problem

A work machine is desired to avoid starting traveling contrary to the intention of an operator, while it is stopped.

The present disclosure proposes a work machine that can suppress performing an operation different from that intended by an operator, and a control system for the work machine.

Solution to Problem

According to an aspect of the present disclosure, a work machine is proposed. The work machine includes: a vehicular body; an engine installed in the vehicular body; a travel device that is attached to the vehicular body and travels by an output of the engine; a travel manipulation device that receives a manipulation of an operator and outputs a travel command to allow the travel device to travel or to stop the travel device; a rotation speed setting device that sets a rotation speed of the engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; a notification device that performs notification to the operator; and a controller. The controller receives an input of the travel command from the travel manipulation device, receives an input of a set value of the rotation speed of the engine from the rotation speed setting device, and receives an input of the seating signal from the seating sensor. When the travel command to allow the travel device to travel is issued, the set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller causes the notification device to perform the notification.

According to an aspect of the present disclosure, a work machine is proposed. The work machine includes: a vehicular body; an engine installed in the vehicular body; a travel device that is attached to the vehicular body and travels by an output of the engine; a travel manipulation device that receives a manipulation of an operator and outputs a travel command to allow the travel device to travel or to stop the travel device; a rotation speed setting device that sets a rotation speed of the engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; and a controller. The controller receives an input of the travel command from the travel manipulation device, receives an input of a set value of the rotation speed of the engine from the rotation speed setting device, and receives an input of the seating signal from the seating sensor. When the travel command to allow the travel device to travel is issued, the set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller makes the travel device unable to travel.

Advantageous Effects of Invention

According to the work machine in accordance with the present disclosure, performing an operation different from that intended by an operator can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of a bulldozer as an example of a work machine based on an embodiment.

FIG. 2 is a plan view schematically showing a partial configuration inside a cab shown in FIG. 1 .

FIG. 3 is a circuit diagram showing a system configuration of the bulldozer of the embodiment.

FIG. 4 is a flowchart showing an example of a method for controlling the bulldozer.

FIG. 5 is a schematic diagram showing an example of a display on a monitor.

FIG. 6 is a flowchart showing a method for controlling a bulldozer of a second embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described based on the drawings. In the description below, identical parts will be designated by the same reference numerals. Since their names and functions are also the same, the detailed description thereof will not be repeated.

First Embodiment <Configuration of Work Machine>

In an embodiment, a bulldozer 10 will be described as an example of a work machine. FIG. 1 is a schematic side view of bulldozer 10 as an example of a work machine based on the embodiment.

As shown in FIG. 1 , bulldozer 10 mainly includes a vehicular body 11, a blade 12 as a work implement, and a travel device 13.

Vehicular body 11 has a cab (an operator’s cab) 18 and an engine compartment 19. Cab 18 is disposed in an upper rear portion of vehicular body 11. An operator who manipulates bulldozer 10 gets into cab 18. Cab 18 has therein an operator seat (driver seat) in which the operator is seated. Engine compartment 19 is disposed in front of cab 18. Engine compartment 19 is disposed between cab 18 and blade 12. An engine 21, for example, an internal combustion engine, which is a motive power source for bulldozer 10, is disposed within engine compartment 19.

In the embodiment, a direction in which bulldozer 10 travels straight is referred to as a forward/rearward direction of bulldozer 10. In the forward/rearward direction of bulldozer 10, a side on which blade 12 protrudes from vehicular body 11 is referred to as a forward direction. In the forward/rearward direction of bulldozer 10, a side opposite to the forward direction is referred to as a rearward direction. A right/left direction of bulldozer 10 is a direction orthogonal to the forward/rearward direction when viewed in a plan view. The right side and the left side in the right/left direction when facing forward are defined as a right direction and a left direction, respectively. An upward/downward direction of bulldozer 10 is a direction orthogonal to a plane defined by the forward/rearward direction and the right/left direction. In the upward/downward direction, the ground side is defined as a lower side and the sky side is defined as an upper side.

Blade 12 is a work implement for performing a work such as excavation and leveling of a ground surface. Blade 12 is disposed in front of vehicular body 11, with a space being interposed between blade 12 and vehicular body 11. Blade 12 has, at its lower edge, a blade edge which is brought into contact with the ground during a work. Blade 12 is supported on both the right and left sides by frames 14. Blade 12 is supported on vehicular body 11 via frames 14.

Each of frames 14 is a member having a quadrangular prism shape. A front end of frame 14 is attached to a rear surface of blade 12 by a rotatable support portion. A rear end of frame 14 is rotatably supported on vehicular body 11.

Blade 12 is driven by a tilt cylinder 15 and a lift cylinder 16. Tilt cylinder 15 and lift cylinder 16 are hydraulic cylinders.

A front end of tilt cylinder 15 is rotatably supported on the rear surface of blade 12. A rear end of tilt cylinder 15 is rotatably supported on an upper surface of frame 14. Tilt cylinder 15 is coupled to frame 14 and blade 12. Due to expansion and contraction of tilt cylinder 15 by hydraulic pressure, an upper edge of blade 12 moves forward and rearward and blade 12 is inclined (tilt movement).

A front end of lift cylinder 16 is rotatably attached on the upper surface of frame 14. A rear end of lift cylinder 16 is rotatably supported on a side surface of vehicular body 11. Due to expansion and contraction of lift cylinder 16 by hydraulic pressure, blade 12 moves in the upward/downward direction (lift movement).

Vehicular body 11 is supported by travel device 13 such that it can travel. Travel device 13 has a pair of crawler travel units spaced apart in the right/left direction. Vehicular body 11 is disposed between the pair of right and left crawler travel units. The right and left crawler travel units each have a drive wheel (sprocket) 13 a, an idler wheel (idler) 13 b, a crawler belt 13 c, and a track frame 13 d.

Drive wheel 13 a and track frame 13 d are attached to a side portion of vehicular body 11. Drive wheel 13 a is disposed behind track frame 13 d such that it can be driven to rotate. Idler wheel 13 b is attached to track frame 13 d. Idler wheel 13 b is rotatably disposed, for example, at a front end portion of track frame 13 d.

Crawler belt 13 c is configured in an annular shape (an endless manner) and is looped over drive wheel 13 a and idler wheel 13 b. Crawler belt 13 c is engaged with drive wheel 13 a and is configured to be rotatable as drive wheel 13 a is driven to rotate. By the rotation of crawler belt 13 c, idler wheel 13 b engages with crawler belt 13 c, and thus can be driven to rotate.

A hydraulic motor 23 included in an HST (Hydraulic Static Transmission) circuit is connected to drive wheel 13 a. A hydraulic pump 22 included in the HST circuit is disposed within engine compartment 19. A charge pump 24 that supplies a hydraulic oil into a parking brake circuit is disposed within engine compartment 19.

FIG. 2 is a plan view schematically showing a partial configuration inside cab 18 shown in FIG. 1 . As shown in FIG. 2 , an operator seat 31 in which the operator who manipulates bulldozer 10 is seated is disposed inside cab 18. Operator seat 31 is disposed substantially near the center of cab 18.

A console 32 is disposed to the left of operator seat 31 inside cab 18. Console 32 is provided with a travel manipulation lever 33 for a travel manipulation of bulldozer 10, a parking brake switch 34 that manipulates activation and release of a parking brake that maintains travel device 13 in a stopped state, a fuel adjustment dial 35 that sets a rotation speed (number of rotations) of engine 21, and the like. The operator seated in operator seat 31 can manipulate travel manipulation lever 33, parking brake switch 34, and fuel adjustment dial 35, with the left hand. Another console not shown is also disposed to the right of operator seat 31, and the console is provided with, for example, a manipulation lever for manipulating blade 12.

A monitor 36 is disposed in front of operator seat 31 inside cab 18. Monitor 36 corresponds to a notification device of the embodiment that displays information and performs notification to the operator. Further, a deceleration/brake pedal 37 for adjusting a vehicle speed of bulldozer 10 is disposed in front of operator seat 31. The operator seated in operator seat 31 can decrease a travel speed of bulldozer 10 by depressing deceleration/brake pedal 37 with a foot and thereby manipulating the same.

<System Configuration>

FIG. 3 is a circuit diagram showing a system configuration of bulldozer 10 of the embodiment. A controller 40 shown in FIG. 3 controls an operation of bulldozer 10. Controller 40 may be mounted in bulldozer 10 to obtain a configuration in which bulldozer 10 includes controller 40. Controller 40 may be disposed outside bulldozer 10, rather than being mounted in bulldozer 10. A control system for bulldozer 10 in which external controller 40 controls bulldozer 10 may be configured. External controller 40 may be disposed at a work site of bulldozer 10, or may be disposed at a remote location away from the work site of bulldozer 10.

Batteries 41 are connected to controller 40. Batteries 41 are electric power sources for controller 40, and electric power is supplied from batteries 41 to controller 40. A battery disconnect switch 42 is provided in a circuit that connects batteries 41 and controller 40. Battery disconnect switch 42 is provided to cut off power supply from batteries 41 to controller 40 during maintenance, when bulldozer 10 is stopped for a long time, and the like.

Bulldozer 10 includes a motive power transmission device that transmits motive power generated by engine 21 to drive wheel 13 a. The motive power transmission device has an HST circuit that transmits motive power by hydraulic pressure. The HST circuit includes hydraulic pump 22, hydraulic motor 23, and a closed hydraulic circuit (closed circuit) that connects hydraulic pump 22 and hydraulic motor 23.

Hydraulic pump 22 is a variable capacity-type hydraulic pump. A drive shaft of hydraulic pump 22 is connected to an output shaft of engine 21, and is rotated by driving engine 21. Hydraulic pump 22 pressurizes an oil within the HST circuit and discharges the oil. Hydraulic pump 22 converts a drive force of engine 21 into energy of the oil (fluid). This energy of the oil is transmitted to hydraulic motor 23.

Hydraulic motor 23 is a variable capacity-type hydraulic motor. A drive shaft of hydraulic motor 23 is connected to an input shaft of drive wheel 13 a. The drive shaft of hydraulic motor 23 is rotated by the oil with high pressure supplied by hydraulic pump 22 being transmitted to hydraulic motor 23, via the closed circuit that connects hydraulic pump 22 and hydraulic motor 23. Rotation of the drive shaft of hydraulic motor 23 is transmitted to drive wheel 13 a, and drive wheel 13 a is rotated. Thus, hydraulic motor 23 converts the inputted energy of the oil into rotation energy (drive energy), and outputs the drive energy to drive wheel 13 a of travel device 13.

The motive power transmission device may include any combination of a transmission, an electrically-powered motor, and the like, instead of being configured to transmit motive power by hydraulic pressure.

Charge pump 24 is a fixed capacity-type hydraulic pump. Charge pump 24 is connected to engine 21. Charge pump 24 is driven by engine 21, and thereby supplies the hydraulic oil to the parking brake circuit.

Travel manipulation lever 33 is manipulated by the operator to set travel device 13 to one of a forward travel state, a rearward travel state, and a neutral state. In FIG. 3 , travel manipulation lever 33 at a neutral position is designated by a numeral 33N and is indicated by a solid line, travel manipulation lever 33 at a forward travel position is designated by a numeral 33F and is indicated by a broken line, and travel manipulation lever 33 at a rearward travel position is designated by a numeral 33R and is indicated by a broken line.

As indicated by a curved line with arrows in FIG. 3 , travel manipulation lever 33 can move from the neutral position to the forward travel position and the rearward travel position. The operator can manipulate travel manipulation lever 33 in a plurality of directions, including one direction from the neutral position toward the forward travel position (for example, the forward direction), and the other direction from the neutral position toward the rearward travel position (for example, the rearward direction).

Travel manipulation lever 33 has a detent mechanism that holds the lever at the forward travel position and rearward travel position, which are positions where the lever is tilted from the neutral position. Even when the operator gets the hand off the lever after manipulating it, travel manipulation lever 33 is held at the neutral position, the forward travel position, or the rearward travel position. When travel manipulation lever 33 is held at the forward travel position, travel device 13 is set to the forward travel state in which it can travel forward. When travel manipulation lever 33 is held at the rearward travel position, travel device 13 is set to the rearward travel state in which it can travel rearward. When travel manipulation lever 33 is held at the neutral position, travel device 13 is set to the neutral state in which it cannot travel and is stopped.

Travel manipulation lever 33 detects at which of the neutral position, the forward travel position, and the rearward travel position travel manipulation lever 33 is located, and outputs a detection result thereof to controller 40. Travel manipulation lever 33 corresponds to a travel manipulation device of the embodiment that receives a manipulation of the operator and outputs a travel command to allow travel device 13 to travel or to stop travel device 13.

Parking brake switch 34 corresponds to a brake manipulation device of the embodiment for manipulating activation and release of a parking brake that maintains travel device 13 in a stopped state. Parking brake switch 34 is a toggle switch, for example. Parking brake switch 34 has internal switches 62 and 63. When the operator manipulates parking brake switch 34 in one direction, internal switch 62 is turned on and internal switch 63 is turned off. When the operator manipulates parking brake switch 34 in the other direction, internal switch 62 is turned off and internal switch 63 is turned on.

Internal switches 62 and 63 each output whether it is on or off, to controller 40. Thereby, a manipulation signal of parking brake switch 34 is inputted into controller 40.

The operator switches between an activation state and a release state of the parking brake, by manipulating parking brake switch 34. For example, the parking brake may be activated when internal switch 62 is turned off and internal switch 63 is turned on, and the parking brake may be released when internal switch 62 is turned on and internal switch is turned off.

Fuel adjustment dial 35 corresponds to a rotation speed setting device of the embodiment that sets the rotation speed of engine 21 by setting the amount of fuel to be supplied to engine 21. The amount of manipulation of fuel adjustment dial 35 by the operator is converted into an electrical signal and is inputted into an engine controller 50. Engine controller 50 controls the rotation speed of engine 21 by supplying an appropriate amount of fuel according to conditions to engine 21. Engine controller 50 is electrically connected with controller 40, and can receive an input of a control signal from controller 40, and output a controlled set value of engine controller 50 to controller 40.

The content of a display on monitor 36 is controlled by controller 40. In response to a command from controller 40 to monitor 36, monitor 36 displays information of the vehicular body, and displays a pop-up display described later.

Deceleration/brake pedal 37 can select two pedal modes, that is, a deceleration mode in which, when the pedal is depressed, the travel speed of bulldozer 10 is decreased and the rotation speed of engine 21 is decreased, and a brake mode in which, when the pedal is depressed, the travel speed of bulldozer 10 is decreased but the rotation speed of engine 21 is not decreased. A potentiometer 69 is attached to a rotation shaft of deceleration/brake pedal 37. Potentiometer 69 detects the angle of rotation of deceleration/brake pedal 37 about the rotation shaft, and thereby detects the amount of depression of deceleration/brake pedal 37 by the operator. Potentiometer 69 outputs a detection result thereof to controller 40.

A parking brake 52 is provided to the drive shaft of hydraulic motor 23. Parking brake 52 has a disc brake portion and a piston portion. Parking brake 52 is configured such that a plurality of discs of the disc brake portion come into contact with each other by a bias force of an elastic member provided to the piston portion, and thereby parking brake 52 is released and travel device 13 can move. When the hydraulic oil is supplied to the piston portion, the piston portion activated by hydraulic pressure keeps the plurality of discs of the disc brake portion from coming into contact with each other. Thereby, parking brake 52 is activated and travel device 13 becomes unmovable. When the hydraulic oil is discharged from the piston portion, parking brake 52 is released by the bias force of the elastic member, and travel device 13 becomes movable.

A rotation speed sensor 53 detects a rotation speed of a drive shaft between parking brake 52 and drive wheel 13 a, and outputs a detection result thereof to controller 40.

The parking brake circuit is an oil flow path that connects charge pump 24 and parking brake 52. Parking brake 52 is provided with parking brake solenoid valves 55 and 56 and a towed valve 57. Parking brake solenoid valve 55 is connected to deceleration/brake pedal 37 and parking brake switch 34, via a limit switch 70. Parking brake solenoid valve 55 is switched between an excited state and a non-excited state, by manipulating parking brake switch 34 and deceleration/brake pedal 37.

Parking brake solenoid valve 56 is switched between an excited state and a non-excited state, according to an input of a control signal from controller 40. Towed valve 57 is normally set to an open state, and is manipulated to be set to a closed state when parking brake 52 is manually released in case of emergency, such as a case where engine 21 has a failure. In the parking brake circuit between towed valve 57 and parking brake 52, a pressure sensor 59 that detects a pressure of the hydraulic oil is provided. Pressure sensor 59 outputs a detection result of the pressure of the hydraulic oil to controller 40.

A seating sensor 61 is provided to operator seat 31. When the operator is seated in operator seat 31, seating sensor 61 is pushed down, and an output value of a voltage from seating sensor 61 to controller 40 is changed. Seating sensor 61 outputs a seating signal indicating a sensed result of whether or not the operator is seated in operator seat 31, to controller 40.

<Method for Controlling Bulldozer 10>

An example of a method for controlling bulldozer 10 of the embodiment having the configuration described above will be described below. FIG. 4 is a flowchart showing an example of a method for controlling bulldozer 10.

As shown in FIG. 4 , in step S1, controller 40 receives an input of a travel command from travel manipulation lever 33 (the travel manipulation device). In a state where the operator is manipulating travel manipulation lever 33 to the forward travel position or the rearward travel position, travel manipulation lever 33 outputs a travel command to allow travel device 13 to travel, to controller 40. In a state where the operator is manipulating travel manipulation lever 33 to the neutral position, travel manipulation lever 33 outputs a travel command to stop travel device 13, to controller 40.

In step S2, controller 40 receives an input of a set value of the rotation speed of engine 21 from fuel adjustment dial 35 (the rotation speed setting device). Fuel adjustment dial 35 stores the set value of the rotation speed of engine 21 according to the amount of manipulation of fuel adjustment dial 35 by the operator. The set value of the rotation speed of engine 21 according to the manipulation by the operator is inputted from fuel adjustment dial 35 to engine controller 50. The set value of the rotation speed of engine 21 is transmitted from engine controller 50 to controller 40.

The set value of the rotation speed of engine 21 according to the amount of manipulation of fuel adjustment dial 35 may be stored in engine controller 50 or controller 40. In this case, the amount of manipulation of fuel adjustment dial 35 is inputted from fuel adjustment dial 35 to engine controller 50, and the set value of the rotation speed of engine 21 is calculated in engine controller 50 or controller 40.

In step S3, controller 40 receives an input of a seating signal indicating a sensed result of whether or not the operator is seated in operator seat 31, from seating sensor 61.

In step S4, controller 40 determines whether or not travel device 13 can travel. When the travel command to allow travel device 13 to travel is inputted from travel manipulation lever 33 in step S1, controller 40 determines that travel device 13 can travel. When the travel command to stop travel device 13 is inputted from travel manipulation lever 33, controller 40 determines that travel device 13 cannot travel.

In step S5, controller 40 determines whether or not the set value of the rotation speed of engine 21 is lower than or equal to a predetermined value. Controller 40 stores a threshold value for the rotation speed of engine 21. Controller 40 compares this threshold value (the predetermined value) with the set value of the rotation speed of engine 21 inputted in step S2.

In step S6, controller 40 determines whether or not the operator is seated in operator seat 31, based on the seating signal inputted in step S3.

When the travel command to allow travel device 13 to travel is issued (YES in step S4), the set value of the rotation speed of engine 21 is lower than or equal to the predetermined value (YES in step S5), and the operator is not seated in operator seat 31 (NO in step S6), the processing proceeds to step S7. Controller 40 outputs, to monitor 36 (the notification device), a control signal to cause monitor 36 to display information to be notified to the operator. Thereby, controller 40 notifies the operator looking at monitor 36 of a manipulation to be performed next, and the like.

FIG. 5 is a schematic diagram showing an example of a display on monitor 36. By the processing in step S7, monitor 36 displays a window 80 shown in FIG. 5 as a pop-up. Window 80 is displayed to overlap with information of the vehicular body and the like displayed on monitor 36. Window 80 includes a title display 81, a pictorial display 82, and a text display 83.

As shown in FIG. 5 , title display 81 displays a detection result of a current situation, i.e., “Leaving Seat Is Sensed with Travel Lever Not Being Set to N”. That is, title display 81 displays a situation where the operator is not seated in operator seat 31 with travel manipulation lever 33 being located at the forward travel position or the rearward travel position, which are positions other than the neutral position.

Pictorial display 82 is a display that expresses the current situation using a picture, to allow the operator looking at pictorial display 82 to easily understand the present situation. As shown in FIG. 5 , there is provided a display briefly showing that the operator is not seated in operator seat 31.

Text display 83 includes a character message that specifically notifies the operator of a manipulation to be performed. Specifically, text display 83 includes a display that prompts a manipulation to locate travel manipulation lever 33 at the neutral position, i.e., “Set Travel Lever to N Position”. Text display 83 includes a display that prompts to manipulate travel manipulation lever 33 to output the travel command to stop travel device 13. Further, text display 83 includes a character message that prompts the operator to sit in operator seat 31, i.e., “Take Seat”.

An alarm 90 shown in FIG. 5 indicates that the notification by monitor 36 (the notification device) involves generation of sound. Alarm 90 is intermittent sound, for example.

Returning to FIG. 4 , in step S8, controller 40 determines whether or not the operator has moved travel manipulation lever 33 to the neutral position according to the display on monitor 36. Controller 40 determines whether or not the travel command to stop travel device 13 has been inputted from travel manipulation lever 33, and thereby determines whether travel manipulation lever 33 remains at forward travel position or the rearward travel position, or travel manipulation lever 33 has been moved to the neutral position. When it is determined that travel manipulation lever 33 is not located at the neutral position (NO in step S8), the determination is repeated.

When it is determined that travel manipulation lever 33 is located at the neutral position (YES in step S8), the processing proceeds to step S9, and the notification to the operator is stopped. Specifically, the pop-up display of window 80 disappears from monitor 36, and the display on monitor 36 returns to the original screen display. Then, the processing is ended (“End” in FIG. 4 ).

When it is determined in the determination in step S4 that the travel command to allow travel device 13 to travel is not issued (NO in step S4), when it is determined in the determination in step S5 that the set value of the rotation speed of engine 21 is more than the predetermined value (NO in step S5), or when it is determined that the operator is seated in operator seat 31 (YES in step S6), the processing is directly ended (“End” in FIG. 4 ), with steps S7 to S9 being skipped.

When the travel command to allow travel device 13 to travel is not issued, travel device 13 does not travel, and thus notification is unnecessary. When the travel command to allow travel device 13 to travel is issued, and the rotation speed of engine 21 is more than the predetermined value, travel device 13 is traveling, and the operator does not leave the seat during traveling, and thus notification is unnecessary. Since the operator seated in operator seat 31 understands the current situation, notification is unnecessary. Therefore, notification to the operator is not performed.

<Function and Effect>

The characteristic configuration and the function and effect of the present embodiment will be summarized below, although the following description may partly overlap with the above description.

Bulldozer 10 of the embodiment includes monitor 36, as shown in FIGS. 2 and 3 . As shown in FIG. 5 , monitor 36 performs notification to an operator. As shown in FIG. 3 , bulldozer 10 includes controller 40. Controller 40 receives an input of a travel command to allow travel device 13 to travel or to stop travel device 13, from travel manipulation lever 33. Controller 40 receives an input of a set value of the rotation speed of engine 21, from fuel adjustment dial 35. Controller 40 receives an input of a seating signal indicating a sensed result of whether or not the operator is seated in operator seat 31, from seating sensor 61. As shown in FIG. 4 , when the travel command to allow travel device 13 to travel is issued, the set value of the rotation speed of engine 21 is lower than or equal to a predetermined value, and the operator is not seated in operator seat 31, controller 40 causes monitor 36 to perform the notification.

Even when travel manipulation lever 33 is located at a forward travel position or a rearward travel position, bulldozer 10 including an HST circuit as a motive power transmission device is stopped by manipulating fuel adjustment dial 35 to set the rotation speed of engine 21 to be lower than or equal to the predetermined value, for example, to the minimum rotation speed. While bulldozer 10 is stopped, the operator may get off bulldozer 10 accidentally. If another operator who subsequently gets into bulldozer 10 manipulates fuel adjustment dial 35 to increase the rotation speed of engine 21 without knowing that travel manipulation lever 33 is located at the forward travel position or the rearward travel position, bulldozer 10 starts traveling contrary to the intention of the operator.

In bulldozer 10 of the embodiment, when the operator stands up from operator seat 31 in an attempt to get off bulldozer 10, the fact that the operator is not seated is sensed, and window 80 that performs notification of information to the operator is displayed on monitor 36. The subsequent operator looks at window 80 displayed on monitor 36, and can recognize a current situation and an action to be taken at present. When the subsequent operator acts according to the display of window 80, even if the subsequent operator thereafter manipulates fuel adjustment dial 35 to increase the rotation speed of engine 21, bulldozer 10 does not start traveling at that moment. Therefore, it is possible to avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

As shown in FIG. 5 , the notification of information to the operator by monitor 36 includes a display that prompts to manipulate travel manipulation lever 33 to output the travel command to stop travel device 13, specifically, a display that prompts to locate travel manipulation lever 33 at a neutral position. By locating travel manipulation lever 33 at the neutral position according to the display of window 80 displayed on monitor 36, it is possible to avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

As shown in FIG. 4 , when controller 40 receives the input of the travel command to stop travel device 13 from travel manipulation lever 33, controller 40 stops the notification. After travel manipulation lever 33 is located at the neutral position to cause bulldozer 10 not to travel contrary to the intention of the operator, window 80 disappears and an ordinary display screen is displayed on monitor 36. Thus, the operator can smoothly start a work.

As shown in FIG. 5 , the notification of information to the operator by monitor 36 includes a display that prompts the operator to sit in operator seat 31. By causing the operator to act according to a duty to wear a seat belt while the operator is in cab 18 of bulldozer 10, the operator can smoothly perform a work using bulldozer 10.

As shown in FIG. 5 , the notification of information to the operator by monitor 36 includes a display of a character message. The operator can reliably recognize a manipulation to be performed, and the like, by reading the character message of text display 83.

As shown in FIG. 5 , the notification of information to the operator by monitor 36 includes generation of sound. By causing monitor 36 or another sound source to generate sound such as alarm 90, it is possible to motivate the operator to check the display on monitor 36, and it is possible to cause the operator to reliably recognize the content of the notification displayed on monitor 36.

As shown in FIGS. 2 and 3 , bulldozer 10 includes parking brake switch 34 that manipulates activation and release of parking brake 52. Controller 40 performs the notification of information to the operator by monitor 36 during the release of parking brake 52. Controller 40 does not perform the notification of information to the operator by monitor 36 during the activation of parking brake 52. Since travel device 13 does not travel during the activation of parking brake 52, notification is unnecessary. Therefore, control can be simplified.

In the case of a conventional configuration in which a parking brake lever is included as a brake manipulation device that manipulates activation and release of parking brake 52, it is possible to make the operator who attempts to get off bulldozer 10 notice that the operator is taking an erroneous action, because the parking brake lever disposed in the path of the operator prevents passage of the operator. In the case of a configuration in which parking brake switch 34 is included instead of the parking brake lever, there is a possibility that the operator may accidentally get off bulldozer 10 without activating parking brake 52, while bulldozer 10 is stopped. However, by displaying information to be notified to the operator on monitor 36, it is possible to more reliably avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

As shown in FIG. 3 , a motive power transmission device that transmits a drive force of engine 21 to travel device 13 has hydraulic pump 22, hydraulic motor 23, and a closed circuit that connects hydraulic pump 22 and hydraulic motor 23. In the case of a configuration in which a torque converter is included in the motive power transmission device, when the travel command to allow travel device 13 to travel is issued, bulldozer 10 continues traveling, even if the rotation speed of engine 21 is set to minimum. Since the operator does not leave the seat during traveling, notification is unnecessary. In the case of a configuration in which bulldozer 10 includes an HST circuit, when the set value of the rotation speed of engine 21 is lower than or equal to the predetermined value, pump capacity is controlled to zero and bulldozer 10 is stopped, even if the travel command to allow travel device 13 to travel is issued. There is a possibility that the operator may accidentally get off bulldozer 10 while bulldozer 10 is stopped. However, by displaying information to be notified to the operator on monitor 36, it is possible to more reliably avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

By applying the configuration of the embodiment to bulldozer 10 that includes blade 12 in front of vehicular body 11 and travels to perform a work as shown in FIG. 1 , it is possible to more reliably avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

The embodiment described above has described an example of the notification to the operator by monitor 36. Notification to the operator who attempts to get off bulldozer 10 and notification to the subsequent operator who gets into bulldozer 10 may be different from each other. For example, to the subsequent operator who gets into bulldozer 10, the notification shown in FIG. 5 can be provided. On the other hand, to the operator who attempts to get off bulldozer 10, a character message that prompts the operator to get off bulldozer 10 after performing appropriate processing to stop bulldozer 10, such as locating travel manipulation lever 33 at the neutral position, or activating parking brake 52, may be displayed before the operator gets off bulldozer 10.

The embodiment described above has described an example in which window 80 is displayed as a pop-up on monitor 36. The notification to the operator is not limited to a pop-up display. For example, a display may be provided on monitor 36 in another display format such as a scroll display. Instead of or in addition to a display on monitor 36, the notification may be performed by sound.

Second Embodiment

FIG. 6 is a flowchart showing a method for controlling bulldozer 10 of a second embodiment. The processing from step S1 to step S6 shown in the flowchart of FIG. 6 is the same as that in FIG. 4 . In the second embodiment, when the travel command to allow travel device 13 to travel is issued (YES in step S4), the set value of the rotation speed of engine 21 is lower than or equal to the predetermined value (YES in step S5), and the operator is not seated in operator seat 31 (NO in step S6), the processing proceeds to step S17. In step S17, controller 40 makes travel device 13 unable to travel.

In bulldozer 10 of the second embodiment, when the operator stands up from operator seat 31 in an attempt to get off bulldozer 10, the fact that the operator is not seated is sensed, and travel device 13 becomes unable to travel. It is possible to make travel device 13 unable to travel, for example, by controlling parking brake solenoid valves 55 and 56 such that controller 40 activates parking brake 52. With such a configuration, even if the subsequent operator manipulates fuel adjustment dial 35 to increase the rotation speed of engine 21, bulldozer 10 does not start traveling at that moment, because travel device 13 is unable to travel. Therefore, it is possible to avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

The description of the embodiments so far has described an example in which the rotation speed of engine 21 is set by a manual manipulation of fuel adjustment dial 35 by the operator. In the case of a configuration in which there is provided an auto deceleration device that decreases the rotation speed of engine 21 when the operator does not perform manipulation, the rotation speed of engine 21 may be decreased to be lower than or equal to the predetermined value due to the activation of the auto deceleration device. Also in this case, when the travel command to allow travel device 13 to travel is issued, and the operator is not seated in operator seat 31, controller 40 causes monitor 36 to perform the notification. Thereby, it is possible to reliably avoid bulldozer 10 from starting traveling contrary to the intention of the operator.

The description of the embodiments so far has described an example in which bulldozer 10 includes cab 18, and seating sensor 61 senses whether or not the operator is seated in operator seat 31 inside cab 18. Cab 18 may not necessarily be provided in vehicular body 11. Also in a case where the bulldozer is a remote-controlled unmanned vehicle without having a cab, there is also a possibility that an operator may leave an operator seat while the bulldozer is stopped. Accordingly, by applying the configuration of the embodiments, it is possible to reliably avoid the bulldozer from starting traveling contrary to the intention of the operator.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the scope of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

REFERENCE SIGNS LIST

10: bulldozer; 11: vehicular body; 12: blade; 13: travel device; 13 a: drive wheel; 18: cab; 19: engine compartment; 21: engine; 22: hydraulic pump; 23: hydraulic motor; 24: charge pump; 31: operator seat; 32: console; 33: travel manipulation lever; 34: parking brake switch; 35: fuel adjustment dial; 36: monitor; 37: deceleration/brake pedal; 40: controller; 41: battery; 42: battery disconnect switch; 50: engine controller; 52: parking brake; 53: rotation speed sensor; 55, 56: parking brake solenoid valve; 57: towed valve; 59: pressure sensor; 61: seating sensor; 62, 63: internal switch; 69: potentiometer; 70: limit switch; 80: window; 81: title display; 82: pictorial display; 83: text display; 90: alarm. 

1. A work machine comprising: a vehicular body; an engine installed in the vehicular body; a travel device that is attached to the vehicular body and travels by an output of the engine; a travel manipulation device that receives a manipulation of an operator and outputs a travel command to allow the travel device to travel or to stop the travel device; a rotation speed setting device that sets a rotation speed of the engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; a notification device that performs notification to the operator; and a controller, wherein the controller receives an input of the travel command from the travel manipulation device, receives an input of a set value of the rotation speed of the engine from the rotation speed setting device, and receives an input of the seating signal from the seating sensor, and when the travel command to allow the travel device to travel is issued, the set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller causes the notification device to perform the notification.
 2. The work machine according to claim 1, wherein the notification by the notification device includes a display that prompts to manipulate the travel manipulation device to output the travel command to stop the travel device.
 3. The work machine according to claim 2, wherein the travel manipulation device includes a manipulation lever that can be manipulated in a plurality of directions, and the notification by the notification device includes a display that prompts to locate the manipulation lever at a neutral position.
 4. The work machine according to claim 2, wherein, when the controller receives the input of the travel command to stop the travel device from the travel manipulation device, the controller stops the notification by the notification device.
 5. The work machine according to claim 1, wherein the notification by the notification device includes a display that prompts the operator to sit in the operator seat.
 6. The work machine according to claim 1, wherein the notification by the notification device includes a display of a character message.
 7. The work machine according to claim 6, wherein the notification by the notification device involves generation of sound.
 8. The work machine according to claim 1, comprising a brake manipulation device that manipulates activation and release of a parking brake that maintains the travel device in a stopped state, wherein the controller performs the notification by the notification device during the release of the parking brake.
 9. The work machine according to claim 8, wherein the brake manipulation device is a switch that can be manipulated by the operator seated in the operator seat.
 10. The work machine according to claim 1, comprising a motive power transmission device that transmits a drive force of the engine to the travel device, wherein the motive power transmission device has a pump that converts the drive force of the engine into energy of a fluid, and a motor that converts the energy of the fluid converted by the pump into drive energy and outputs the drive energy to the travel device.
 11. The work machine according to claim 1, wherein the work machine is a bulldozer including a blade in front of the vehicular body.
 12. A work machine comprising: a vehicular body; an engine installed in the vehicular body; a travel device that is attached to the vehicular body and travels by an output of the engine; a travel manipulation device that receives a manipulation of an operator and outputs a travel command to allow the travel device to travel or to stop the travel device; a rotation speed setting device that sets a rotation speed of the engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; and a controller, wherein the controller receives an input of the travel command from the travel manipulation device, receives an input of a set value of the rotation speed of the engine from the rotation speed setting device, and receives an input of the seating signal from the seating sensor, and when the travel command to allow the travel device to travel is issued, the set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller makes the travel device unable to travel.
 13. A control system for a work machine, the control system comprising: a vehicular body; an engine installed in the vehicular body; a travel device that is attached to the vehicular body and travels by an output of the engine; a travel manipulation device that receives a manipulation of an operator and outputs a travel command to allow the travel device to travel or to stop the travel device; a rotation speed setting device that sets a rotation speed of the engine; a seating sensor that outputs a seating signal indicating a sensed result of whether or not the operator is seated in an operator seat; a notification device that performs notification to the operator; and a controller, wherein the controller receives an input of the travel command from the travel manipulation device, receives an input of a set value of the rotation speed of the engine from the rotation speed setting device, and receives an input of the seating signal from the seating sensor, and when the travel command to allow the travel device to travel is issued, the set value of the rotation speed of the engine is lower than or equal to a predetermined value, and the operator is not seated in the operator seat, the controller causes the notification device to perform the notification. 